$A$ $75 \, m$ long train is moving at $20 \, km/h$. It will cross a man standing on the platform in (in $sec$):

$A$ person covers half of his journey at $30 \text{ km/h}$ and the remaining half at $20 \text{ km/h}$. The average speed for the whole journey is (in $\text{km/h}$)

$A$ man starts from a place $P$ and reaches the place $Q$ in $7 \, hours$. He travels $\frac{1}{4}^{th}$ of the distance at $10 \, km/h$ and the remaining distance at $12 \, km/h$. The distance,in $km$,between $P$ and $Q$ is

An express train travelled at an average speed of $100 \, km/hr$, stopping for $3 \, minutes$ after every $75 \, km$. How long did it take to reach its destination $600 \, km$ from the starting point?

Train $A$ starts its journey from Patna to Hazipur while train $B$ starts from Hazipur to Patna. After crossing each other, they finish their journey in $81\, \text{hours}$ and $121\, \text{hours}$ respectively. What will be the speed of train $B$ if the speed of train $A$ is $44\, \text{km/h}$?

$A$ train takes $18 \, s$ to pass completely through a station $162 \, m$ long and $15 \, s$ through another station $120 \, m$ long. The length of the train (in $m$) is: